Sunday, 9 April 2017

BRODIE BRIDGE MILEAGE 65.2 / 65.0 - Part 1

On March 19 our post provided a comprehensive look at the junction station of Brodie on the Kettle Valley Division.  A reader has asked about the girder bridge and it happens to be on our list of projects to build for our miniature Brodie junction.  So the following provides additional information, drawings and photographs on this Merritt Subdivision bridge at Brodie, identified as Bridge Mileage 65.2 for our favoured era and later on as Mileage 112.9 of the Princeton Sub.  Our field notes state it was erected by Dominion Bridge Co. and Joe Smuin in Kettle Valley Mileboards states that this happened in 1931/1932 to replace the original wooden Howe Truss Span.  We will deal with the bridge itself in this and the next post but the concrete abutments are complicated and irregular and will not be given much attention here.  In the photo above, note that the abutments are open whereas later views such as the next photo, reveal that concrete has been added to enclose the ends of the bridge.

As must be obvious, this action shot was taken from the running board of one of the last Princeton way freights in March of 1989 on which the author was privileged to ride from Merritt to Princeton and return thanks to Helmut, a now retired CPR dispatcher.  We have here a good view of the ties, the alignment of which is staggered due to the bridge being situated on a 12 degree curve.  That is about 65 1/2" radius in HO and 36" in N scale.

  This view is unavailable today as the rail has been lifted and the ties are covered with two layers of lumber to more safely accommodate the many hikers and cyclists who travel the Cross-Canada Trail much of which traverses the abandoned right-of-way of the late Kettle Valley and Kootenay Divisions of the CPR.  The author has made numerous field trips to the site of the bridge recording various details in photograph and measurement.  Fortunately, we acquired from the CPR engineering department some drawings to supplement the field information and find that the two sources largely corroborate each other.  It is hoped that our study will enable some enterprising modelers to reproduce this interesting piece of engineering or variations thereof.
This close-up crop reveals the method in which the CPR painted the designated mileage numbers on the end of steel girder bridges.  It must be noted that this number conflicts a little with other documents that denote the bridge as Mileage 65.0.  After abandonment of the Coquihalla Subdivision in 1961 the Brodie bridge became Mileage112.9 of the Princeton Subdivision but those digits are nowhere evident in any of our photos or entered in our field notes.

From our files we present details from a drawing of a standard CPR One Hundred Foot Through Plate Girder Span.  It differs from our subject bridge in one major particular but that will be easily explained so that the construction details should be useful to modelers in this and other bridge projects.  The drawing will be presented in sections so that the measurements and notes will be legible.  It bears a date of December 26, 1929!  No boxing day holiday for the drafting department that year.  Here is the Title Block with some basic specifications.
The  Elevation and Plan Views with major components labelled in red.

From these two portions of the drawing and others, the specifications of the main structural members are deciphered as follows:
2 Main Girders measuring 10'-1 1/4" high x 18" wide x 102"-9" long overall, each built up of 6 sections and 2 short end plates. Each girder composed of:
  • 6 webs 10'-0" high x 3/8" thick x 16'-7 3/4" long
  • 5 Splice plates 14" wide
  • 19+ L's or angles 6" x 3 1/2" (stiffeners)
  • 5 cover plates 5/8" to 1/2" thick top and bottom
  • 2 end plates with web of 1'-4 1/2" wide and L's (stiffeners)
7 Floor Beams @ 44" high x 12 1/2" wide x  17'-11" (approx.) overall built up of
  • web 44" high x 7/16" thick x 12'-11" long connected to the Main Girders by L's
  • splice plates
  • extension plates
  • L's or angles 8" x 6 1/2" & cover plate 13"
12 Stringers @ 33" high x  12" x 16'-7" (approx.)
  • "Carnegie Beam" i e,  a solid "I" beam (not built up)
  • Connected with L's 8" x 8" to Floor Beam
  • Ties rest on these members
12 Struts which were Solid Channels 18" high x 4" wide x 7'-10 1/2" long
  • connected to the Stringers by L's
Lateral Bracing or diagonals were L's 6" x 4" x 3/8"
  • connected to the main girders and floor beams by various shaped Gussets (see plan for shape and size).
We conclude this study of the standard bridge plans with the End and Cross-Section views from the CPR drawings.

The next post will deal with the particulars and details of the actual bridge at Brodie.  For now, the modeler can examine the components with a view to acquiring the necessary materials for constructing a model of this 100 Foot Through Plate Girder Span.  Styrene will be the medium when the project is undertaken by Coquihalla Man.

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